title: The effect of multiple chronic conditions on self-rated health, disability and quality of life among the older populations of Northern Ireland and the Republic of Ireland: a comparison of two nationally representative cross-sectional surveys.
abstract: OBJECTIVE
  Multimorbidity is common in the older population, but the impact of combinations of chronic conditions on disability and quality of life (QoL) is not well known. This analysis explores the effect of specific combinations of chronic diseases on disability, QoL and self-rated health (SRH).
  
  
  METHODS
  We used data from two population representative cross-sectional studies, the Northern Ireland Health and Social Wellbeing Survey (NIHSWS) 2005 and the Survey of Lifestyle, Attitudes and Nutrition (SLAN) 2007 (conducted in the Republic of Ireland).
  
  
  METHODS
  Randomly selected community-living participants were interviewed at home.
  
  
  METHODS
  A total of 6159 participants aged 50 years and older were included in the analysis.
  
  
  METHODS
  Chronic conditions were classified as cardiovascular disease, chronic pain, diabetes or respiratory disease. Interaction terms estimated by logistic regression were used to examine the effects of multiple chronic conditions on disability, SRH and QoL.
  
  
  RESULTS
  Each chronic condition group was correlated with each of the others after adjusting for sociodemographic factors. Those from Northern Ireland were more likely to report a limitation in daily activities (45%) compared to those from the Republic of Ireland (21%). Each condition had an independent effect on disability, SRH and QoL, and those with multiple chronic conditions reported the worst outcomes. However, there were no statistically significant positive interactions between chronic condition groups with respect to any outcome.
  
  
  CONCLUSIONS
  Chronic conditions affect individuals largely independent of each other with respect to their effect on disability, SRH and QoL. However, a significant proportion of the population aged 50 years and over across the island of Ireland lives with multimorbidity, and this group is at the highest risk of disability, poor SRH and poor QoL.
authors.affiliation: Centre for Health Policy and Management, Trinity College Dublin, Dublin, Republic of Ireland.
authors.forename: Olga
authors.initials: O
authors.lastname: McDaid
authors.forename: Mark J
authors.initials: MJ
authors.lastname: Hanly
authors.forename: Kathryn
authors.initials: K
authors.lastname: Richardson
authors.forename: Frank
authors.initials: F
authors.lastname: Kee
authors.forename: Rose Anne
authors.initials: RA
authors.lastname: Kenny
authors.forename: George M
authors.initials: GM
authors.lastname: Savva
keywords: Epidemiology; Geriatric Medicine; Statistics & Research Methods